You will still be able to run any software on your computer once it has booted, the signature is for the bootloader. So this would only be an issue if Wikileaks for some reason had to implement their own operating system. Even then, users would have the option to disable secure boot and run the unsigned bootloader.
..Unless you run on an ARM chipset, at least in the case of Windows. I don't advocate government intervention often, but I would really like to see that particular requirement struck down on antitrust grounds.
